The iPhone Dev-Team has posted that just release iPhone OS 3.0 beta 5 is already jailbroken and also warned against updating.

iPhone Dev-Team: Apple just released the fifth beta of their 3.0 OS. Back when 2.0 was still in beta, they released about nine beta firmwares, so it’s reasonable to assume we’re about half way through the 3.0 beta process.

As should be expected, the modern devteam jailbreak process is still valid. The picture below is 3.0beta5 jailbroken on an iPhone 3G. As we’ve said in previous posts, nothing other than a hardware respin can prevent our jailbreak from working on all exisiting iPhone and iPod Touches. They’ve chased our jailbreak so far down in the chain of trust, the only way they can fix it is in hardware.

Because there are so many beta releases, we couldn’t possible refine, test, and release both PwnageTool and QuickPwn for each of them. That’s why we’re waiting until the final release. You may have seen other “hijacked” versions of QuickPwn out there, but all of them are buggy, none of them work on OSX, and almost everyone who uses them reverts back to 2.2.1 (because none of the useful jailbroken apps (Qik, Cycorder, and others) work on 3.0 yet).

But this is a good time to remind everyone. If you care about the yellowsn0w unlock, don’t go anywhere near the beta releases. You will lose your unlock, possibly forever.